"It is not clear when the Rammas Echor was built. According to the text it was "after Ithilien fell under the shadow of their Enemy." (RotK, p. 22) This could be taken to mean when the Nazgul captured Minas Ithil in 2002 of the Third Age, or when Uruks attacked Ithilien in 2901, or when the last inhabitants of Ithilien fled in 2954.

But according to Tolkien's unfinished index the Rammas Echor was built during the reign of Denethor II, who became Steward in 2984. (Reader's Companion, p. 512) In order to reconcile this with the statement in the text, the wall may have been built as late as 3018 after Sauron's forces recaptured Osgiliath in June. In this case, the work being done on the wall on March 9, 3019, may have been the completion of the Rammas Echor rather than repairs to a damaged section."